AutoCodes – Nissan – P0138 2006 Nissan Pathfinder

P0138 2006 Nissan Pathfinder Code - HO2S12 Circuit High Voltage

Quick Answer

The Heated Oxygen Sensor 2 (HO2S) (Rear O2 Sensor), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. Common causes include Faulty Rear Heated Oxygen Sensor Bank 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: P0138 2006 Nissan Pathfinder indicates HO2S12 Circuit High Voltage.
Common causes: Common causes include Faulty Rear Heated Oxygen Sensor Bank 1, Rear Heated Oxygen Sensor Bank 1 harness is open or shorted, Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 4,706

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 25, 2024

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0138 2006 Nissan Pathfinder Description

The Heated Oxygen Sensor 2 (HO2S) (Rear O2 Sensor), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. For optimum catalyst operation, the air fuel mixture (air-fuel ratio) must be maintained near the ideal stoichiometric ratio. The HO2S output voltage changes suddenly in the vicinity of the stoichiometric ratio. The Engine Control Module (ECM) adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric. The HO2S generates a voltage between 0.1 and 0.9 V in response to oxygen in the exhaust gas. If the oxygen in the exhaust gas increases, the air-fuel ratio becomes Lean. The ECM interprets Lean when the HO2S voltage is below 0.45 V. If the oxygen in the exhaust gas decreases, the air-fuel ratio becomes Rich. The ECM interprets Rich when the HO2S voltage is above 0.45 V.

OBDII Code P0138 2006 Nissan Pathfinder - HO2S12 Circuit High Voltage - AutoCodes.com — P0138 2006 Nissan Pathfinder Code - HO2S12 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0138 2006 Nissan Pathfinder?

Faulty Rear Heated Oxygen Sensor Bank 1
Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
Intake air leaks
Exhaust gas leaks
Inappropriate fuel pressure
Faulty fuel injectors

How to Fix the DTC P0138 2006 Nissan Pathfinder?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

Replacing the Rear Heated Oxygen Sensor Bank 1 usually takes care of the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0138 2006 Nissan Pathfinder code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0138 2006 Nissan Pathfinder Code

1. What does OBDII code P0138 on a 2006 Nissan Pathfinder mean?

- OBDII code P0138 indicates that the HO2S12 (Heated Oxygen Sensor Bank 1 Sensor 2) circuit is registering a high voltage condition.

2. What are the common symptoms of a P0138 code in a 2006 Nissan Pathfinder?

- Common symptoms include poor fuel economy, rough idling, engine misfires, and the illumination of the check engine light.

3. What are the possible causes of a HO2S12 circuit high voltage in a 2006 Nissan Pathfinder?

- Potential causes include a faulty oxygen sensor, exhaust leaks, wiring issues, a malfunctioning PCM (Powertrain Control Module), or an overly rich fuel mixture.

4. How can I diagnose the cause of a P0138 code in my 2006 Nissan Pathfinder?

- Diagnosing a P0138 code typically involves inspecting the oxygen sensor wiring, checking for exhaust leaks, testing the sensor's voltage output, and scanning for related codes.

5. Can a P0138 code be triggered by a bad oxygen sensor in a 2006 Nissan Pathfinder?

- Yes, a faulty oxygen sensor can cause a P0138 code by sending incorrect voltage readings to the PCM.

6. What are some repair tips for addressing a P0138 code in a 2006 Nissan Pathfinder?

- Repair options may include replacing the HO2S12 sensor, repairing any damaged wiring, fixing exhaust leaks, or reprogramming the PCM if necessary.

7. Is it safe to continue driving with a P0138 code in a 2006 Nissan Pathfinder?

- It is generally not recommended to continue driving with a P0138 code, as it can lead to decreased fuel efficiency and potential damage to the catalytic converter.

8. How much does it typically cost to repair a P0138 code in a 2006 Nissan Pathfinder?

- The cost of repairing a P0138 code can vary depending on the specific issue, but it may range from $100 to $400 or more, including parts and labor.

9. Can I reset the check engine light after repairing a P0138 code on my 2006 Nissan Pathfinder?

- Yes, after repairing the underlying issue causing the P0138 code, you can reset the check engine light using an OBDII scanner or by disconnecting the car battery for a few minutes.

10. How often should I replace oxygen sensors in a 2006 Nissan Pathfinder to prevent P0138 codes?

- Oxygen sensors typically have a lifespan of around 50,000 to 100,000 miles and should be replaced as part of regular maintenance to prevent issues like the P0138 code.